The invention is directed to a process for the recovery of pure nicotinamide from crude nicotinamide by recrystallization in alkanol. The invention particularly is directed to a process for freeing the nicotinamide from the impurities nicotinic acid and salts of nicotinic acid, e.g. sodium nicotinate, ammonium nicotinate and potassium nicotinate.
Nicotinamide is generally produced by hydrolysis of nicotinonitrile in acid or alkaline medium or by reaction of nicotinic acid with ammonia. The crude nicotinamide obtained in this process of production contains impurities, especially nicotinic acid (generally about 0.3 to 5.0%) and salts of nicotinic acid (generally about 1.5 to 2.5%). These impurities create problems in the further use of the nicotinamide, namely in the pharmaceutical area, especially if their amount exceeds 0.1%.
It is known to purify crude nicotinamide with the help of an ion exchange resin (British Pat. No. 879551 and Finkelstein U.S. Pat. No. 3,678,060). These processes are expensive and besides only give a sufficiently pure nicotinamide under a considerable loss of yield. It is also known to purify crude nicotinamide by recrystallization. As solvents in this case there are employed acetone (Duesel, U.S. Pat. No. 2,471,518), propanol-2 or butyl acetate in the presence of decolorizing carbon (German Pat. No. 828247), ethyl acetate (Krewson, J. Amer. Chem. Soc., Vol. 65, pages 2256-2257 (1943)), ethanol in the presence of activated carbon (Galat, J. Amer. Chem. Soc., Vol. 70, page 3945 (1948)), dioxane or petroleum ether (Pike U.S. Pat. No. 2,412,749) or benzene (Danish Pat. No. 87228).
A disadvantage of these processes is that for the production of a sufficiently pure nicotamide multiple recrystallization is required and only a moderate yield of pure nicotinamide is produced.